No full table scan
Querying x$ksmhp with a full table scan (like for example select * from x$ksmhp) does not return a record.
In order to find records, it must be queried with a valid heap descriptor (address) on the column ksmchds.
Valid heap descriptors can be found (among others?) in
x$kglcursor:
select kglobhd6 from x$kglcursor;
…
00007FFB3D4DDAE0
…
With such a heap descriptor, the corresponding records can be queried like so:
select
addr,
ksmchcom chunk_allocation_comment,
ksmchptr chunk_pointer,
ksmchsiz chunk_size,
ksmchcls allocation_class,
ksmchtyp chunk_type,
ksmchpar,
ksmchown,
indx,
inst_id,
con_id
from
x$ksmhp
where
ksmchds = hextoraw('00007FFB3D4DDAE0');